Pressure compensated venturi dispensing system

ABSTRACT

Systems, methods, and software program products for dispensing chemical solutions. A controller receives a signal from a pressure sensor indicative of a pressure of a diluent. The controller determines an expected flow rate of the diluent through an eductor based at least in part on the pressure of the diluent. The controller may further determine an expected concentration of a chemical product in the solution dispensed from a discharge port of the eductor. Based on the expected flow rated and concentration of the chemical product, the controller determines a duration of a dispense stage of a dispensing operation required to dispense a predetermined dose of the chemical product. The controller then causes the diluent to flow through the eductor for the determined duration of the dispense stage. A check valve on the output of the eductor prevents dissimilar chemicals from mixing and reduces a response time of the eductor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to co-pending U.S.Application No. 62/558,499 filed Sep. 14, 2017, the disclosure of whichis incorporated by reference herein in its entirety.

BACKGROUND

The present invention generally relates to dispensing systems, and inparticular, to systems, methods, and computer program products fordispensing chemical solutions using an eductor based chemical dispenser.

Eductors are devices that pass a liquid through a choke to generate theVenturi effect. The suction generated by the Venturi effect is used todraw another liquid into the eductor. For example, water running throughthe eductor may cause a chemical product to be drawn into the eductor,where it mixes with the water and is subsequently discharged as a dilutesolution. Eductors are often used to mix chemical products with water indispensing systems to produce small batches of chemical solutions. Thesebatches of chemical solutions may be discharged into a container forlater use, a washing machine, or some other apparatus or process thatrequires dilute chemical solutions.

One problem with dispensing systems that use eductors is that thepressure of the diluent used to feed the eductors must be above aminimum level to produce adequate suction on the chemical inlet side ofthe eductor. If the pressure falls below the minimum level, the amountof chemical product drawn into the eductor may be insufficient for theresulting solution to perform properly. Moreover, the concentration ofthe chemical product in the chemical solution discharged from theeductor can vary with the pressure of the diluent across a wide range ofoperating pressures. This can lead to solutions being specified athigher concentrations than needed to ensure that acceptable levels ofchemicals are in the solution when the diluent pressure is at the lowend of the operating range of pressures. Another problem with dispensingsystems that use eductors is that the internal channels of the eductorcan become clogged, which can also affect the concentration of chemicalsin the chemical solution discharged by the eductor.

Therefore, there is a need for improved systems, methods, and computerprogram products for dispensing chemical solutions using eductors thatprovide solutions with more consistent concentrations.

SUMMARY

In an embodiment of the invention, a dispensing system is provided. Thesystem includes a controller configured to perform a dispensingoperation, an eductor, and a pressure sensor. The dispensing operationincludes a dispense stage having a duration. The eductor includes aninlet port that is selectively fluidically coupled to a source of adiluent by the controller during the dispense stage, and a dischargeport configured to discharge a chemical solution during the dispensestage. The pressure sensor is configured to provide a first signalindicative of a pressure of the diluent to the controller, and thecontroller determines the duration of the dispense stage based at leastin part on the pressure of the diluent.

In another aspect of the dispensing system, the system further includesa concentration sensor configured to provide a second signal to thecontroller indicative of a characteristic of the diluent or the chemicalsolution, and the controller determines the duration of the dispensestage based at least in part on the characteristic.

In another aspect of the dispensing system, the characteristic is aconcentration of a substance in the diluent or the chemical solution.

In another aspect of the dispensing system, the substance is a mineraland the duration of the dispense stage is proportional to theconcentration of the substance.

In another aspect of the dispensing system, the substance is a chemicalproduct, and the duration of the dispense stage is inverselyproportional to the concentration of the substance.

In another aspect of the dispensing system, the controller is furtherconfigured to capture a sequence of readings indicative of thecharacteristic, compare the sequence of readings to a predeterminedpattern associated with the dispensing operation, and if the sequence ofreadings is not in accordance with the predetermined pattern, determinethere is a problem with the dispensing operation.

In another aspect of the dispensing system, the dispensing operationincludes a flush stage, and the controller is further configured todetermine the duration of the flush stage based at least in part on thepressure of the diluent.

In another aspect of the dispensing system, the dispensing operation isdefined by a dose of the chemical product and a total volume of solutionto be dispensed, and the controller is further configured to determine aflow rate of the diluent through the eductor based at least in part onthe pressure of the diluent, determine a concentration of the chemicalproduct in the solution discharged by the eductor based at least in parton the pressure of the diluent, and determine the duration of thedispense stage based at least in part on the dose of the chemicalproduct, the concentration of the chemical product in the chemicalsolution discharged by the eductor, and the flow rate of the diluentthrough the eductor.

In another aspect of the dispensing system, the controller is furtherconfigured to determine a volume of the chemical solution discharged bythe eductor during the dispense stage based at least in part on theduration of the dispense stage and the flow rate of the diluent, anddetermine the duration of the flush stage based at least in part on adifference between the volume of the chemical solution discharged duringthe dispense stage and the total volume of solution to be dispensed.

In another embodiment of the invention, a method of dispensing asolution is provided. The method comprises receiving the first signalindicative of the pressure of the diluent, determining the duration ofthe dispense stage of the dispensing operation based at least in part onthe pressure of the diluent, and causing the diluent to flow through theeductor for the determined duration of the dispense stage.

In another aspect of the method, the method further includes receivingthe second signal indicative of the characteristic of the diluent or thechemical solution discharged from the discharge port of the eductor, anddetermining the duration of the dispense stage based at least in part onthe characteristic.

In another aspect of the method, the characteristic is the concentrationof the substance in the diluent or chemical solution.

In another aspect of the method, the substance is the mineral, and theduration of the dispense stage is proportional to the concentration ofthe substance.

In another aspect of the method, the substance is the chemical product,and the duration of the dispense stage is inversely proportional to theconcentration of the substance.

In another aspect of the method, the method further includes capturingthe sequence of readings indicative of the characteristic during thedispensing operation, comparing the sequence of readings to thepredetermined pattern associated with the dispensing operation, and ifthe sequence of readings is not in accordance with the predeterminedpattern, determining there is a problem with the dispensing operation.

In another aspect of the method, the dispensing operation includes theflush stage, and the method further comprises determining the durationof the flush stage based at least in part on the pressure of thediluent.

In another aspect of the invention, the dispensing operation is definedby the dose of the chemical product and the total volume of solution tobe dispensed, and the method further comprises determining the flow rateof the diluent through the eductor based at least in part on thepressure of the diluent, determining the concentration of the chemicalproduct in the solution discharged by the eductor based at least in parton the pressure of the diluent, and determining the duration of thedispense stage based at least in part on the dose of the chemicalproduct, the concentration of the chemical product in the solutiondischarged by the eductor, and the flow rate of the diluent through theeductor.

In another aspect of the invention, the method further comprisesdetermining the volume of the solution discharged by the eductor duringthe dispense stage based at least in part on the duration of thedispense stage and the flow rate of the diluent, and determining theduration of the flush stage based at least in part on the differencebetween the volume of the solution discharged during the dispense stageand the total volume of solution to be dispensed.

In another embodiment of the invention, a computer program product forperforming the dispensing operation is provided. The computer programproduct comprises a non-transitory computer-readable storage medium andprogram code stored on the non-transitory computer-readable storagemedium. The program code is configured to, when executed by one or moreprocessors, cause the one or more processors to receive the first signalindicative of the pressure of the diluent, determine the duration of thedispense stage of the dispensing operation based at least in part on thepressure of the diluent, and cause the diluent to flow through theeductor for the determined duration of the dispense stage.

In another embodiment of the invention, another dispensing system ispresented. The dispensing system comprises a flush manifold including aplurality of intake ports, the eductor, and a check valve. The eductorincludes the inlet port that is selectively fluidically coupled to thesource of the diluent, a pickup port fluidically coupled to a source ofthe chemical product, and the discharge port configured to discharge thechemical solution in response to the diluent being coupled to the inletport. The check valve couples the discharge port of the eductor to oneof the intake ports of the flush manifold.

In another aspect of the dispensing system, the check valve comprises anupstream chamber, a downstream chamber fluidically coupled to theupstream chamber by an opening, and a closing member configured tofluidically isolate the downstream chamber from the upstream chamber bycovering the opening absent a flow of fluid from the upstream chamber tothe downstream chamber.

In another aspect of the dispensing system, the check valve furthercomprises an elastic member that urges the closing member into contactwith the opening absent the flow of fluid from the upstream chamber tothe downstream chamber.

In another aspect of the dispensing system, the opening is defined by avalve seat.

In another aspect of the dispensing system, the check valve provides adynamic flood ring that has a first resistance to the flow of fluidthrough the eductor in a first state, and a second resistance to theflow of fluid higher than the first resistance in a second state.

In another aspect of the dispensing system, the first state is an openstate and the second state is a closed state.

In another aspect of the dispensing system, the check valve maintainsthe eductor in a flooded state when the dynamic flood ring is in thesecond state.

In another embodiment of the invention, another method of performing thedispensing operation is presented. The method includes providing a flowof liquid to the inlet port of the eductor sufficient to flood theeductor, in response to the flow of liquid being provided to the inletport, providing the first resistance to the flow of liquid out of thedischarge port of the eductor, and in response to the flow of liquid tothe inlet port being reduced, providing the second resistance to theflow of liquid out of the discharge port.

In another aspect of the method, the first resistance is lower than thesecond resistance.

In another aspect of the method, the first resistance optimizes suctionat the pickup port of the eductor, and the second resistance maintainsthe eductor in the flooded state.

In another aspect of the method, providing the first resistancecomprises moving the closing member out of contact with the opening inresponse to the flow of liquid, the movement compressing the elasticmember, and providing the second resistance comprises moving the closingmember into contact with the opening in response to urging by theelastic member.

The above summary presents an overview of some embodiments of theinvention to provide a basic understanding of certain aspects theinvention discussed herein. The summary is not intended to provide anextensive overview of the invention, nor is it intended to identify anykey or critical elements, or delineate the scope of the invention. Thesole purpose of the summary is merely to present some concepts in asimplified form as an introduction to the detailed description presentedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate various embodiments of theinvention and, together with the general description of the inventiongiven above, and the detailed description of the embodiments givenbelow, serve to explain the embodiments of the invention.

FIG. 1 is a diagrammatic view of an operating environment of anexemplary dispensing system including a controller and a dispenserhaving a concentration sensor in accordance with an embodiment of theinvention.

FIG. 2 is a diagrammatic view of an admittance probe including a currentsource and a buffer amplifier that may be used to implement theconcentration sensor of FIG. 1.

FIG. 3 is a diagrammatic view of an embodiment of the admittance probeof FIG. 2 showing additional details of the current source and bufferamplifier.

FIG. 4 is a graphical view showing the refractive index of a solutionthat may be dispensed by the dispensing system of FIG. 1 with respect tothe concentration of a chemical product in the solution.

FIG. 5 is a diagrammatic view of an optical probe that may be used toimplement the concentration sensor of FIG. 1.

FIG. 6 is a diagrammatic view of another optical probe that may be usedto implement the concentration sensor of FIG. 1.

FIGS. 7A and 7B are diagrammatic views of yet another optical probe thatmay be used to implement the concentration sensor of FIG. 1.

FIG. 8 is a diagrammatic view of yet another optical probe that may beused to implement the concentration sensor of FIG. 1.

FIG. 9 is a front view of a dispenser in accordance with an embodimentof the invention.

FIG. 10 is a bottom view of the dispenser of FIG. 9.

FIG. 11 is a back view of the dispenser of FIG. 9.

FIG. 12 is a perspective view of the dispenser of FIG. 9.

FIG. 13 is an exploded perspective view of the dispenser of FIG. 9.

FIG. 14 is an exploded perspective view of a controller in accordancewith an embodiment of the invention.

FIG. 15 is a front view of a portion of a dispenser in accordance withan embodiment of the invention that includes check valves which couple aplurality of eductors to a flush manifold.

FIG. 16 is cross-sectional view of a portion of the dispenser in FIG.15.

FIG. 17 is a cross-sectional view of one of the check valves of FIGS. 15and 16.

DETAILED DESCRIPTION

FIG. 1 depicts an exemplary operating environment for a dispensingsystem 10 in accordance with an embodiment of the invention. Thedispensing system 10 includes a controller 12 and a dispenser 14, and isconfigured to dispense chemical solutions to a point of use, such as awashing machine 16, through a dispense line 17. The operatingenvironment of the dispensing system 10 may include one or more sourcesof a chemical product 18, 20 that are fluidically coupled to thedispenser 14. Exemplary chemical products 18, 20 may include chemicalssuch as detergents, water softening agents, bleaches, and the like. Eachsource of chemical product 18, 20 may include a level sensor 22, 24 thatprovides a signal indicative of a level of chemical product 18, 20remaining in the source to the controller 12.

The controller 12 may include a Human Machine Interface (HMI) 26, aprocessor 28, an input/output (I/O) interface 30, and a memory 32. TheHMI 26 may include output devices, such as an alphanumeric display, atouch screen, and/or other visual and/or audible indicators that provideinformation from the processor 28 to a user of the dispensing system 10.The HMI 26 may also include input devices and controls, such as analphanumeric keyboard, a pointing device, keypads, pushbuttons, controlknobs, etc., capable of accepting commands or input from the user andtransmitting the entered input to the processor 28.

The processor 28 may include one or more devices configured tomanipulate signals (analog or digital) based on operational instructionsthat are stored in memory 32. Memory 32 may be a single memory device ora plurality of memory devices including but not limited to read-onlymemory (ROM), random access memory (RAM), volatile memory, non-volatilememory, static random-access memory (SRAM), dynamic random-access memory(DRAM), flash memory, cache memory, or any other device capable ofstoring information. Memory 32 may also include a mass storage device(not shown), such as a hard drive, optical drive, tape drive,non-volatile solid-state device or any other device capable of storingdigital information.

Processor 28 may operate under the control of an operating system 34that resides in memory 32. The operating system 34 may manage controllerresources so that computer program code embodied as one or more computersoftware applications 36 (such as a dispensing operation application)residing in memory 32 may have instructions executed by the processor28. In an alternative embodiment, the processor 28 may execute theapplications 36 directly, in which case the operating system 34 may beomitted. One or more data structures 38 may also reside in memory 32,and may be used by the processor 28, operating system 34, and/orapplication 36 to store data.

The I/O interface 30 operatively couples the processor 28 to othercomponents in the operating environment, such as the dispenser 14,washing machine 16, and level sensors 22, 24. The I/O interface 30 mayinclude signal processing circuits that condition incoming and outgoingsignals so that the signals are compatible with both the processor 28and the components to which the processor 28 is coupled. To this end,the I/O interface 30 may include analog to digital (A/D) and/or digitalto analog (D/A) converters, voltage level and/or frequency shiftingcircuits, optical isolation and/or driver circuits, and/or any otheranalog or digital circuitry suitable for coupling the processor 28 tothe other components in the operating environment.

The I/O interface 30 may be coupled to the washing machine 16 by amachine interface 40. The machine interface 40 may be configured totransform high voltage trigger signals generated by the washing machine16 into lower voltage signals suitable for the I/O interface 30 ofcontroller 12 and transmit these low voltage trigger signals to thecontroller 12. The signals may be transmitted over one or more dedicatedsignal lines, e.g., using a multi-conductor cable, or over a signalserial data line. For embodiments using a serial data line tocommunicate with the controller 12, the machine interface 40 may furtherinclude a processor, a memory in communication with the processor, and auser interface that enables programing of the machine interface 40 totranslate trigger signals into a suitable serial communication protocol.Machine interfaces are described in U.S. Pat. No. 9,447,536, issued Sep.20, 2016, the disclosure of which is incorporated by reference herein inits entirety.

The dispenser 14 may include an inlet manifold 42, a flush manifold 44,and one or more selector valves 46. Each selector valve 46 mayselectively fluidically couple the inlet manifold 42 to an inlet port 50of a respective eductor 48 in response to a signal received from thecontroller 12. In addition to the inlet port 50, each eductor 48 mayfurther include a discharge port 52 fluidically coupled to an intakeport 53 of the flush manifold 44, and a pickup port 54 fluidicallycoupled to a feed line 56 from one of the one or more sources ofchemical product 18, 20. In an embodiment of the invention, one or moreof the pickup ports 54 may be coupled to the feed line 56 by a checkvalve 58 to prevent a back-flow from the flush manifold 44 into thesource of chemical product 18, 20.

The inlet port 50 may be coupled to the discharge port 52 by one or morepassages that are configured to produce suction at the pickup port 54 inresponse to a flow of diluent through the eductor 48. The eductor 48 mayoperate by forcing the diluent through a conical body that creates apressure differential between the inlet port 50 and discharge port 52.This pressure differential may generate a vacuum inside the eductor 48that, in turn, generates suction at the pickup port 54. An exemplaryeductor 48 that may be suitable for use in embodiments of the inventionis described in U.S. Pat. No. 6,634,376, issued Oct. 21, 2003, thedisclosure of which is incorporated by reference herein in its entirety.

The inlet manifold 42 may include an input port 59 that is coupled to asource of diluent 60 by an inlet valve 62 and/or a pressure regulator64. The pressure regulator 64 may regulate the pressure of the diluent60 provided to the inlet manifold 42. The inlet valve 62 may beconfigured to selectively couple the inlet manifold 42 to the source ofdiluent 60 in response to signals from the controller 12. The pressureregulator 64 may be configured to maintain the pressure of the diluent60 in the inlet manifold at a constant level so long as the pressureprovided by the source of diluent 60 remains above a minimum level.

The pressure of the diluent 60 in the inlet manifold 42 may affect therate at which diluent 60 flows through the eductors 48. By isolating theinlet manifold 42 from variations in diluent pressure provided by thesource of diluent 60, the pressure regulator 64 may reduce variances inthe concentration of solutions provided to the point of use. Forexample, regulating the pressure of the diluent may prevent solutionsprovided to the point of use from being “leaned out” beyond theirdesired concentration levels by excessive diluent flow levels throughthe eductors 48.

The dispenser 14 may further include a pressure sensor 66 locateddownstream of the inlet valve 62, such as in the inlet manifold 42. Thepressure sensor 66 may be configured to sense the pressure of thediluent 60 on an inlet manifold side of the inlet valve 62 and provide asignal 67 indicative of the sensed pressure to the controller 12. Onesensor that may be suitable for use as pressure sensor 66 is the PX26series pressure sensor available from Omega Engineering of Stamford,Connecticut, United States. The pressure sensor 66 may dynamically sensechanges in the pressure of the diluent 60 during a dispensing operationthat includes one or more dispense and/or flush stages. Monitoring thepressure of the diluent 60 during a dispensing operation may enable thecontroller 12 to sense a drop of inlet manifold pressure (e.g., due to adrop in the pressure provided by the source of diluent 60) during thedispensing operation, which may cause a corresponding drop in a flowrate of the diluent 60 through the active eductor 48.

The pressure sensor 66 may be located proximate to a flush valve 70and/or the selector valve 46 that is used to perform flush stages. Thepressure sensor 66 may be operated by an excitation voltage (e.g., a 10V DC voltage), and may output the signal 67 (e.g., millivolt rangevoltage) indicative of the pressure sensed by the pressure sensor 66,e.g., a voltage that is proportional to the incoming diluent pressure.The signal 67 may be coupled to the processor 28 via the I/O interface30 to provide the processor 28 with information on pressure with respectto time during operation of the dispensing system 10. The output signalmay be routed to the processor 28 on a local printed circuit board or toa remotely operated controller 12.

The dispenser 14 may further include a concentration sensor 68configured to detect the concentration of one or more substances (e.g.,chemical product, mineral salt, and/or other substance) in the diluent60 and/or dispensed solutions and provide a signal 71 indictive of theconcentration to the controller 12. The concentration sensor 68 mayinclude an optical probe and/or a conductive probe and may be located inthe flush manifold 44 (depicted) or another point downstream of theeductors 48. For example, the concentration sensor 68 may be built intoan output port 72 of flush manifold 44. In an alternative embodiment ofthe invention, the concentration sensor 68 and/or an additionalconcentration sensor (not shown) may be located in the inlet manifold 42and used to determine concentrations of substances in the diluent 60prior to mixing with the chemical products 18, 20. Advantageously,locating the concentration sensor 68 in the flush manifold 44 may allowthe dispensing system 10 to monitor multiple dispense channels andprovide solutions to multiple points of use using a single concentrationsensor 68 rather than separate sensors that detect the concentration ofthe chemical product for each individual chemical and/or point of use.

The signal 71 provided to the controller 12 by concentration sensor 68may be used to determine a characteristic of the solution in the flushmanifold 44, such as the concentration of one or more substances (e.g.,calcium carbonate and/or magnesium) that contribute to the hardness inthe diluent 60 and/or the concentration of one or more of the chemicalproducts 18, 20. The signal 71 may be an analog signal (e.g., voltage orcurrent) and/or a digital signal. For embodiments in which the signal isa digital signal, the concentration sensor 68 may include electroniccircuitry that quantifies the characteristic, e.g., as a concentrationlevel in parts-per-million. The controller 12 may be configured tosample the signal 71 and store these samples and/or the concentrationsdetermined therefrom in memory 32 as a sequence of readings indicativeof the characteristic. The concentration sensor 68 may allow thecontroller 12 to adjust the amount of chemical product dispensed to thepoint of use during the dispensing operation to account for waterhardness and/or variations in chemical product flow rates through theeductors 48. The dispensing system 10 may thereby provide more effectivesolutions as compared to dispensing systems lacking the concentrationsensor feature.

In an embodiment of the invention, the concentration sensor 68 maycomprise a conductivity probe having electrodes that detect theconductivity of liquids in the flush manifold 44. The conductivity probemay provide a signal to the controller 12 in the form of an impedance,voltage, or current level indicative of the detected conductivity. Thecontroller 12 may be configured to determine the conductivity of theincoming diluent, e.g., during a pre-dispense stage or post-dispensestage flush of the flush manifold 44. Conductivity probes and methods ofdetermining the conductivity of a solution are described in U.S. Pat.No. 8,926,834 issued Jan. 6, 2015, the disclosure of which isincorporated by reference herein in its entirety.

The flush valve 70 may selectively fluidically couple the inlet manifold42 to the flush manifold 44 in response to signals from the controller12. This may allow the controller 12 to execute flush stages beforeand/or after activating the selector valves 46 to dispense chemicalsolutions. These flush stages may be used to clear the flush manifold 44of chemical solutions between dispense stages, transport previouslydispensed chemical solutions to the point of use, and/or provide adesired amount of diluent 60 to the point of use. In an alternativeembodiment of the invention, this flushing feature may be enabled bycapping the pickup port 54 of one of the eductors 48 (e.g., the eductor48 furthest from the output port 72 of flush manifold 44) and activatingthe respective selector valve 46 to flush the flush manifold 44. In thiscase, the flush valve 70 may be omitted.

The controller 12 may respond to a sensed drop in the pressure of thediluent 60, for example, by increasing an amount of time the respectiveselector valve 46 is kept open. This change in the duration of thedispense stage may compensate for a leaning out of the chemical solutionby increasing the volume of the chemical solution provided to the pointof use. The leaning out may be due to a reduction in the rate thechemical product 18, 20 is drawn into pickup port 54 caused by a lowerflow rate of diluent 60 through the eductor 48 than would have occurredif the pressure of the diluent 60 had not dropped.

The increase in duration of the dispense stage may be determined by thecontroller 12 based on a known function of the flow rate of the pickupport 54 versus the flow rate of diluent 60 through the eductor 48. Theflow rate of diluent 60 through the eductor 48 may be determined by thecontroller 12 based on a known function of the flow rate through theeductor 48 verses diluent pressure at the inlet port 50. In analternative embodiment of the invention, the period of time may bedetermined using a predefined algorithm (e.g., a lookup table) that mapsthe flow rate of chemical product 18, 20 into the pickup port 54 to thepressure at the inlet port 50. The controller 12 may thereby alter thedispensing operation to compensate for pressure changes in the diluent60 so that the correct dose of chemical product 18, 20 is delivered tothe point of use.

To keep the total volume of the solution delivered to the point of useconsistent between dispensing operations, the controller 12 may adjustthe volume of diluent 60 dispensed during a subsequent flush stage tocompensate for changes in the volume of the chemical solution dispensedduring the dispense stage. For example, the duration of a post-dispenseflush stage may be determined based on a difference between the totalvolume of solution to be dispensed to the point of use during thedispensing operation, and the volume of the chemical solution/diluentdispensed during any prior flush and/or dispense stages.

During a dispense stage of a dispensing operation, the chemical product18, 20 injected into the diluent 60 flowing through the eductor 48 maychange the conductivity, refractive index, fluorescent properties,and/or other characteristics of the diluent 60. Thus, the chemicalsolution dispensed during the dispense stage may have a differentconductivity and/or refractive index than the diluent 60 dispensedduring a flush stage. After the dispense stage, the controller 12 mayexecute a flush stage to help remove any residual chemical product fromthe flush manifold 44, and/or to transport the chemical solution to thepoint of use. This flush stage may be executed at the end of thedispensing operation, and may return the conductivity and/or refractiveindex sensed by the concentration sensor 68 back to a value associatedwith the diluent 60.

If the controller 12 fails to detect changes in the concentration,conductivity, and/or optical characteristics of the solution flowingthrough the flush manifold 44 in accordance with a predetermined patternfor the dispensing operation being performed, the controller 12 maydetermine that a source of chemical product 18, 20 is running low or hasrun out, or that there is some other problem with the dispensing system.The characteristics of the solution flowing through the flush manifold44 may be in accordance with the predetermined pattern if thecharacteristics are within a predetermined threshold of an expectedvalue at one or more points in time during the dispensing operation.

In response to a determination the characteristics are not in accordancewith the predetermined pattern, the controller 12 may alert the user asto which source of chemical product 18, 20 and/or dispensing channelappears to have an issue. The controller 12 may also disable activationof the selector valve 46 associated with that source of chemical product18, 20 until the event is cleared. Advantageously, the concentrationsensor 68 may be used in this way to determine the status of each sourceof chemical product 18, 20 being used. The ability to detect theconcentration of chemical products in the flush manifold using thesingle concentration sensor 68 may allow the dispensing system to avoidplacing individual sensors on each feed line 56 to detect the presenceof absence of chemical product.

In an alternative embodiment of the invention, the controller 12 may usea demultiplexer to control the dispenser 14 rather than the processor28. In this embodiment, the demultiplexer may be used to implement logicfunctions that operate the dispenser 14. In another alternativeembodiment of the invention, the dispenser 14 may include an interfacecircuit 74 (FIG. 10). The interface circuit 74 may communicate with thecontroller 12 using a serial data line. The interface circuit 74 may beconfigured to receive data from the controller 12 over the serial dataline, and to activate/deactivate valves 46, 70 based on the receiveddata. The interface circuit 74 may be further configured to transmitdata to the controller 12 using the serial data line. The transmitteddata may be indicative of signals generated by various sensors 66, 68.The interface circuit 74 may also use flow regulator and/or detectiondevices to monitor the pressure of the source of diluent 60 and transmitthese readings to the controller 12. This may enable the controller 12to adjust the period of time the selector valves 46 and/or inlet valve62 is activated when the sensed pressure is inadequate to produce fullsuction in one or more of the eductors 48.

By way of example, the pressure regulator 64 may be configured so thatthe pressure at the pressure sensor 66 is normally at a level (e.g., 30PSI) that allows the eductors 48 to generate their rated suction whenthe selector valve 46 is open. When an event occurs that drops thepressure of the diluent 60, such as another draw on the source ofdiluent 60, the controller 12 may detect the pressure drop based on achange in the signal generated by the pressure sensor 66. In response todetermining that the inlet manifold pressure has dropped below theminimum pressure at which the eductors 48 generate rated suction, thecontroller 12 may generate an alarm using the HMI 26 or some otherindicator, e.g., a buzzer or light. The controller 12 may alsocompensate for the reduced suction at the pickup port 54 of the activeeductor 48 by keeping the selector valve 46 open for a longer period oftime as described above. For dispensing systems using a common diluentinlet line, a single pressure sensor 66 may be used for all dispensingoperations. The controller 12 may also be configured to verify thedispensing system 10 is operating properly based at least in part on theoutput of the concentration sensor 68.

Dispensing events, such as changes in the pressure of the diluent 60,concentration levels of substances in the diluent 60 and/or dispensedsolution, and/or low chemical product conditions, may be logged inmemory 32 for later analysis, and may also trigger visual and/or audiblealarms to notify the user of the event.

FIG. 2 depicts an admittance probe 76 that may comprise all or part ofthe concentration sensor 68 in accordance with an embodiment of theinvention. The admittance probe 76 may include a plurality of electrodes78, 80 coupled to a current source 82 and to the inputs 84, 86 of abuffer amplifier 88. The electrodes 78, 80 may be formed from anysuitable conductive material, such as Hastelloy, which is a corrosionresistant nickel-molybdenum-chromium alloy available from HaynesInternational, Inc. of Kokomo, Indiana, United States. The outputimpedance of the current source 82 and the impedance of the inputs 84,86 of buffer amplifier 88 may be high, e.g., on the order of severalmegaohms. The current provided by the current source 82 may be a pulsedcurrent having an amplitude on the order of a microamp. The admittanceprobe 76 may further include an output resistor 90 (e.g., a 30 kΩresistor) that provides a path for the current of the current source 82and to set the impedance between the electrodes 78, 80. In an embodimentof the invention, the output resistor 90 may represent the outputimpedance of the current source 82. The buffer amplifier 88 may beconfigured to output a low impedance signal 92 indicative of a voltageacross the electrodes 78, 80 and/or output resistor 90.

FIG. 3 depicts an exemplary embodiment of the admittance probe 76 inwhich the current source 82 includes an operational amplifier 75 and atransistor 77. The operational amplifier 75 may include an invertinginput 75 a, a non-inverting input 75 b, and an output 75 c. Thetransistor 77 may include a collector 77 a, a base 77 b, and an emitter77 c. The inverting input 75 a of operational amplifier 75 may becoupled to a positive voltage source +V (e.g., V_(CC)) by a biasingresistor 79 (e.g., a 470 Ω resistor) and to a negative voltage source −V(e.g., ground) by another biasing resistor 81 (e.g., a 4.7 kΩ resistor).The non-inverting input 75 b of operational amplifier 75 may be coupledto the collector 77 a of transistor 77.

The collector 77 a of transistor 77 and the non-inverting input 75 b ofoperational amplifier 75 may be coupled to the positive voltage source+V by another biasing resistor 83 (e.g., a 470 Ω resistor). The output75 c of operational amplifier 75 may be coupled to the base 77 b oftransistor 77. The emitter 77 c of transistor 77 may be coupled to theelectrode 78 and provide the output of the current source 82. A resistor85 (e.g., a 100 kΩ resistor) may couple the electrode 80 to the negativevoltage source −V and provide a path for the current output by currentsource 82 in the event the electrodes 78, 80 are in a high impedanceenvironment.

The buffer amplifier 88 may include one or more operational amplifiers87, 89, 91 each including a respective non-inverting input 87 a, 89 a,91 a, inverting input 87 b, 89 b, 91 b, and output 87 c, 89 c, 91 c. Thenon-inverting inputs 87 a, 89 a of operational amplifiers 87, 89 may becoupled to respective electrodes 78, 80 by respective input resistors93, 95 (e.g., 100 kΩ resistors). The outputs 87 c, 89 c of operationalamplifiers 87, 89 may be coupled to their respective inverting inputs 87b, 89 b so that the operational amplifiers 87, 89 provide unity gainvoltage follower input stages of the buffer amplifier 88.

The output 87 c of operational amplifier 87 may be coupled to thenon-inverting input 91 a of operational amplifier 91 by a resistor 97(e.g., a 110 kΩ resistor) and the output 89 c of operational amplifier89 may be coupled to the inverting input 91 b of operational amplifier91 by another resistor 99 (e.g., a 110 kΩ resistor). The non-invertinginput 91 a of operational amplifier 91 may be coupled to the negativevoltage supply −V by a resistor 101 (e.g., a 220 kΩ resistor), and theinverting input 91 b may be coupled to the output 91 c of operationalamplifier 91 by a feedback resistor (e.g., a 220 kΩ resistor) to providea differential amplifier output stage.

In operation, the controller 12 may determine the electrical admittanceof the liquid (e.g., chemical solutions and/or diluent 60) in the flushmanifold 44 on a periodic basis based on the signal 92 output by theadmittance probe 76. This process may be distinguished from conventionalmeasurements using a conductivity type concentration sensor, whichtypically includes a voltage source that operates continuously.Advantageously, using a current source 82 to determine an admittancevalue of liquids in the flush manifold 44 may avoid the need tocharacterize mechanical constants of the admittance probe 76, the sizeor configuration of the electrodes 78, 80, spatial relationships betweenthe tips of the electrodes 78, 80, or temperature correction algorithmsthat compensate for changes in the signal 92 due to variations in thetemperature of the liquid.

The admittance probe 76 may be configured to detect the admittance ofthe solution being dispensed proximate to the output port 72 of flushmanifold 44. Because only a portion of the electrodes 78, 80 must be incontact with the solution being measured, the circuitry (e.g., currentsource 82 and buffer amplifier 88) may be located remotely from theelectrodes 78, 80, e.g., on the printed circuit board of the controller12.

The admittance probe 76 may have several advantages over sensors usingvoltage sources. For example, the high output impedance of the currentsource 82 may avoid measurement errors that could otherwise be caused byfilms or coatings forming on the electrodes 78, 80. That is, anyadditional series resistance (e.g., several hundred or several thousandohms) caused by coatings on the electrodes 78, 80 may be insignificantcompared to the high input impedance of admittance probe 76. The highoutput impedance of the current source 82 may avoid the need tocompensate for temperature and resistive losses causes by long wireleads between the current source 82 and the electrodes 78, 80. Longleads can also add parasitic capacitance, which in turn may causeconventional monitoring circuits to oscillate. The signal 92 output bythe admittance probe 76 may allow the controller 12 to detect changes(e.g., a drop) in the concentration of the ions in a solution based onchanges in ionic conduction through the solution as the dispensedchemicals mix with the diluent 60.

The current source 82 may be inactive until a measurement is to be made.In response to receiving power or some other suitable signal (e.g., fromthe controller 12), the current source 82 may output one or more pulsesof current to the electrodes 78, 80. The admittance probe 76 may includea controlled power-on time that provides a pulsed current signal to theelectrodes 78, 80, thereby enabling the concentration sensor 68 to beactivated by the application of power. The pulsed current signal mayreduce any effects of polarization that could contribute to fouling ofthe electrodes 78, 80. Changes in the admittance of the solution in theflush manifold 44 may be revealed by the microamp level pulsed signal,any may have a direct correlation to the admittance value of any type ofconductive liquid. The signal resulting from the current pulse may beread and converted to a format that can be transmitted to the controller12, e.g., a voltage and/or frequency component. The output signal 92 maybe coupled to an analog-to-digital (A/D) converter of the I/O interface30, to an integrated A/D converter in the processor 28, and/or a captureand compare I/O port. The controller 12 may use the admittanceinformation to make changes to the dispensing operation on the fly asthe characteristics diluent 60 and/or chemical solutions change during adispensing operation.

During installation of the dispensing system 10, a calibration processmay be performed during which diluent 60 at a predetermined pressure isprovided to the inlet manifold 42. The controller 12 may include acalibration mode that allows the user to measure the admittance of thesolution in the flush manifold 44 while each eductor 48 is dispensingchemical. While operating in the calibration mode, the controller 12 maysample the output signal 92 and store the sampled value in a nonvolatilememory location for each chemical dispensed. This value may then be usedas a reference value to help determine if the dispensing system 10 isoperating properly. For example, during operation of the chemicaldispenser, the admittance probe 76 may measure the admittance value ofthe chemical product 18, 20 and diluent 60 mixture. These admittancevalues may be compared to the admittance values measured duringinstallation to verify that the active eductor 48 is operating properly.

The controller 12 may use data obtained from the pressure sensor 66 andconcentration sensor 68 independently or in combination to provide areliable closed loop dispensing process during all or part of thedispensing operation. If the concentration measurements (e.g., theadmittance or optical characteristics of the solution as indicated byoutput signal 71) do not follow the pattern of concentration verses timedefined during the calibration process, the controller 12 may determinethat the diluent pressure at the inlet manifold 42 has changed, e.g., istoo low. The controller 12 may verify this determination based onreadings from the pressure sensor 66. If the output signal of thepressure sensor 66 indicates that the diluent pressure level is in avalid operating range when the concentration levels are incorrect, itmay be indicative that the chemical product 18, 20 is running low (e.g.,if the concentration levels are moving over a range of values as slugsof chemical are periodically drawn in to the eductor 48) or has run out(e.g., if the concentration levels are consistently low). In response todetecting a low chemical product condition, the controller 12 may alertthe user as to which chemical product is having a problem via the HMI26. The controller 12 may also prevent activation of the selector valvefor that chemical channel until the low chemical product condition iscleared.

The controller 12 may be configured to display current values of thediluent pressure in the inlet manifold 42 and/or characteristics of thesolution in the flush manifold 44 on the HMI 26. The above data, as wellas other operational data of the dispensing system 10, may betransmitted to a user device, such as a smart phone or tablet, over anetwork, e.g., a wireless Wi-Fi or Bluetooth network. The I/O interface30 of controller 12 may also include a serial data port that enables thecontroller 12 to communicate locally to a personal computer or otherwired network-based device. The dispensing system 10 may therebyindicate the occurrence of a dispensing event visually, audibly, orboth, on the HMI 26 of controller 12 or on the user interface of a userdevice.

FIG. 4 depicts an exemplary graph 103 including a horizontal axis 105 acorresponding to a concentration of a chemical product, such as LusterProfessional detergent, which is available from Procter & Gamble Inc. ofCincinnati Ohio, a vertical axis 105 b corresponding to a refractiveindex of the solution, data points 109 a-109 d indicative of therefractive index at specific concentrations of the chemical product, anda plot 111 showing a linear approximation of the refractive index of thesolution relative to the concentration of the chemical product in thesolution. The plot 111 may be, for example, a line determined byapplying the least-squares analysis to the data points 109 a-109 d.

As can be seen from the graph 103, the addition of the chemical productto the diluent changes its refractive index. The refractive index of asolution may vary from a base refractive index (e.g., n=1.333 for purewater) to that of the chemical solution (e.g., n=1.412 for Lusterdetergent), with the amount of the change dependent on the concentrationof the chemical product in the solution. For example, chemical solutionsdispensed to a washing machine may have a refractive index of between1.37 to 1.49 depending on the chemical product and concentration thereofin the solution. The refractive indexes, or a value of a signalindicative thereof, for individual chemical products may be determinedempirically at various concentration levels. These values may be storedas a look up table in memory 32 of controller 12, e.g., during acalibration process, and used to determine concentration levels of thedispensed solutions during operation of the dispensing system 10. Incases where the refractive index of the diluted chemical product changesin a generally linear fashion with respect to the level of dilution, itmay also be possible to mathematically predict the refractive index.This prediction may be based upon the volume of diluent and the amountof the chemical solution being pumped through the output section takinginto consideration a volume of the cross-sectional area.

In an embodiment of the invention, the concentration sensor 68 maycomprise an optical probe. FIGS. 5-8 depict exemplary embodiments of anoptical probe 94 that may be used to detect concentrations of substancesbased on the refractive index of the solution. For example, in additionto the effects of chemical products discussed above, it has beendetermined that calcium carbonate and magnesium each uniquely affect therefraction index of the diluent 60, and that this effect on therefraction index of the diluent 60 may be detected optically.

Referring now to FIGS. 5 and 6, the optical probe 94 may include aholder 96, a light source 98, and one or more (e.g., two) photodetectors100, 102. The holder 96 may be configured to locate the light source 98and photodetectors 100, 102 in a fixed position relative to a chamber104 which the solution being measured flows through or otherwise enters.The holder 96 may include one or more channels 106-108 that provide oneor more optical paths for a beam of light 110 emitted by the lightsource 98. Each of the channels 106-108 coupling the light source 98 andphotodetectors 100, 102 to the chamber 104 may include an aperture112-114 that defines an opening having a predetermined size and shape.For example, the source channel 106 may include a circular aperture 112having a diameter of 2 mm or less, and the photodetector channels 107,108 may each include a circular aperture 113, 114 having a diameter of 3mm or less.

The apertures 112-114 may be defined by baffles formed in the channel106-108 as depicted in FIGS. 5 and 6, or by the diameter of the channel106-108 itself. The apertures 112-114 may be configured to allow thebeam of light 110 to reach one or the other of the photodetectors 100,102 when the solution in the chamber 104 has a refractive index nspecific to that photodetector (e.g., n=1.3 or 1.0), and may shield thephotodetectors 100, 102 from the beam of light 110 when the medium inthe chamber 104 has a different refractive index.

The chamber 104 may include one or more walls 116 that isolate the othercomponents of the optical probe 94 from the medium in the chamber 104,and that have a refractive index the same as or different from themedium in the chamber 104. The optical probe 94 may be configured todetect concentrations of minerals in the diluent 60 by selecting thedimensions (e.g., T₁, T₂, T₃), refractive indexes, and relativelocations of the components of the optical probe 94. The configurationof the optical probe 94 may cause the displacement 118 of the beam oflight 110 to align the beam of light 110 with a respective photodetector100, 102 when the medium in the chamber 104 has a specific concentrationof a mineral or a chemical product being measured. Optical probes thatwork based on changes in refractive index are described in applicationSer. No. 15/689,255, entitled OUT-OF-PRODUCT DETECTION USING OPTICALSENSORS and filed on Aug. 29, 2017, the disclosure of which isincorporated by reference herein in its entirety.

FIGS. 7A and 7B depict an alternative embodiment of the optical probe 94that includes a light source 115, a sensor 117, an optical element 119(e.g., a prism), a source mask 121 including a horizontal slot 123, anda detector mask 125 including a vertical slot 127. The light source 115may include a light emitting diode, such as narrow beam infrared lightemitting diode, or any other suitable source of light. The opticalelement 119 may be made from a transparent material (e.g., glass orplastic) and include a source facing surface 129, a solution facingsurface 131 that is optically coupled to a solution 133 (e.g., asolution in the interior of flush manifold 44), and a sensor facingsurface 135 that faces the sensor 117. The source mask 121 may belocated between the light source 115 and the source facing surface 129of optical element 119 so that the horizontal slot 123 couples light 137from the light source 115 into the optical element 119.

The horizontal slot 123 may be configured so that the light 137 isincident on and distributed relatively evenly across the inward facingside of the solution facing surface 131. As a result, the angle ofincidence θ_(i) between the light 137 and a line normal to the surface131 may increase with the distance from the horizontal slot 123 to thesurface 131. For given indexes of refraction for the optical element 119and the solution 133, at a specific point indicated by dashed line 139,the angle of incidence θ_(i) may reach the critical angle θ_(c). Atangles of incidence θ_(i) less than the critical angle θ_(c) (i.e., tothe left of dashed line 139), the majority of the light 137 incident onthe solution facing surface 131 may pass into the solution 133. However,at angles of incidence θ_(i) greater than critical angle θ_(c) (i.e., tothe right of dashed line 139), there may be total internal reflectionthat causes the majority of the light 137 to be reflected downwardtoward the sensor 117 by the solution facing surface 131. The criticalangle θ_(c) may be determined using the following equation:

$\begin{matrix}{\theta_{C} = {\arcsin \left( \frac{n_{2}}{n_{1}} \right)}} & {{Eqn}.\mspace{14mu} 1}\end{matrix}$

where n₁ is the refractive index of the optical element 119 and n₂ isthe refractive index of the solution 133.

Thus, for an optical element 119 having a fixed refractive index (e.g.,n₁=1.53), as the refractive index n₂ of the solution 133 increases(e.g., from n₂=1.37 to n₂=1.49), the location where the light 137incident on the solution facing surface 131 has an angle of incidenceθ_(i) equal to the critical angle may move from right to left along thesolution facing surface 131 of optical element 119. This movement isdepicted by the position of the dashed line 139 shifting from right toleft between FIGS. 7A and 7B. The increase in the critical angle θ_(c)may further result in the reflected light covering a greater portion ofthe sensor 117, as shown by the increased number of reflected rays inFIG. 7B as compared to FIG. 7A. Thus, the refractive index of thesolution 133 may be inferred by the position and/or size of theilluminated section of the sensor 117.

Advantageously, embodiments of the optical probe 94 using the criticalangle to detect the refractive index n₂ of solution 133 can be used toprovide feedback to the controller 12 on the both the type of chemicalproduct and the duration of the chemical product dispense cycle. Theinformation regarding the refractive index n₂ of solution 133 may alsobe used to determine if there is an issue with the chemical product,such as a low or out of product condition.

Embodiments of the optical probe 94 that rely on critical angles todetermine the refractive index of solution 133 are not limited to theexemplary embodiment depicted in FIGS. 7A and 7B. For example, theoptical element 119 could have dimensions and angles other than those ofthe right-angle prism depicted. Optical elements having shapes otherthan that of a prism or having multiple components could also be used.For example, an optical window could be used to couple the solution toand/or in place of the optical element 119. Although depicted as beingoriented perpendicular/parallel to their respective facing surfaces 129,133, the light source 115 and/or sensor 117 could also be oriented atother angles with respect to the surfaces 129, 133 of optical element119.

The sensor 117 may include a linear array (e.g., 128×1) of photodiodesor pixels and associated circuitry that allows charge to build up for aselectable period of time on the photodiodes. The sensor 117 may beoriented generally parallel to the sensor facing surface 135 of opticalelement 119 to capture the arc of the rays exiting the optical element119. The refractive index n₂ of the solution 133 may be determined basedon the size of the arc that hits the sensor 117. The sensor 117 mayoutput an analog voltage at the end of a sampling cycle indicative ofthe intensity of light incident on one or more pixels of the array. Thissignal may be transmitted to the controller 12 and used by thecontroller to determine refractive index n₂ of the solution 133 beingmonitored.

FIG. 8 depicts an alternative embodiment of the optical probe 94 that isconfigured to detect minerals and/or other substances that fluorescewhen exposed to short wavelength light, e.g., Ultra-Violet (UV) light.The optical probe 94 may include a holder 120, an exciting light source122, and a photodetector 124. The holder 120 may be configured to locatethe light source 122 and photodetector 124 in a fixed position (e.g., adistance and angle) relative to each other and a chamber 126 which thesolution being measured flows through or otherwise enters. The holder120 may include channels 128, 130 that provide an optical path for abeam of light 132 emitted by the light source 122, and fluorescent light134 emitted by substances in response to being excited by the beam oflight 132.

The chamber 126 may include one or more walls 136 that isolate the othercomponents of the optical probe 94 from the medium in the chamber 126.The optical probe 94 may be configured to detect concentrations ofsubstances in the diluent 60 based on the amount of fluorescent light134 that is detected by the photodetector 124. The optical probe 94 maythereby enable the controller 12 to determine the concentration ofsubstances, such as minerals that contribute to water hardness, whichmay have a direct effect on the cleaning capability of the solution andthe amounts of chemicals that should be dispensed into the diluent 60.

However configured, the optical probe 94 may be used by the controller12 to determine an equivalent part-per-million level of minerals in thediluent 60. This feedback to the controller 12 on the quality of thediluent may allow the controller 12 to adjust the amount of chemicalsdispensed, e.g., dispensing additional chemicals to compensate for adiluent 60 having a high mineral content, and/or dispensing lesschemicals if the diluent 60 has a low mineral content. This compensationfor the mineral content of the diluent 60 may be performed, for example,in a laundry application to which the prescribed amount of detergent isbased on the size and type of the laundry load and that assumes thedosing amount is correct based on a certain water hardness level.

FIGS. 9-13 depict front, bottom, back, perspective, and exploded views,respectively of a dispenser 140 in accordance with an embodiment of theinvention. As best shown by FIG. 13, the dispenser 140 includes theinlet manifold 42, flush manifold 44, selector valves 46, eductors 48,check valves 58, and interface circuit 74. The dispenser 140 furtherincludes a user interface 141 (which may be provided by the HMI 26 ofcontroller 12) and a housing 142 having a front portion 144 and a backportion 146.

The front portion 144 of housing 142 may include openings 154, 156 thatprovide access to the user interface 141, and the back portion 146 ofhousing 142 may include openings 158 that provide access to input ports160 of check valves 58. Opening 154 may provide access to a display 162that displays information about the operation of the dispenser 140 tothe user, and one or more input devices 164 (e.g., buttons) that enablethe user to provide data/instructions to the dispenser 140. Opening 156may include a removeable cover 166 that provides access to a serial dataport 168, such as a Universal Serial Bus (USB) port, which is anindustry standard communication protocol managed by the USB ImplementersForum. Dispensing Systems including USB ports are described in U.S. Pat.No. 8,956,579, issued Feb. 17, 2015, the disclosure of which isincorporated by reference herein in its entirety.

The back portion 146 of housing 142 may include one or more openings 170each configured to receive a keeper 172. A mounting bracket 174 may beconfigured to be mounted to a wall or other support structure, and mayinclude one or more slots 176 each configured to receive one of thekeepers 172. In operation, the mounting bracket 174 may be affixed tothe support structure, and the back portion 146 of housing 142positioned over the mounting bracket 174. One of the keepers 172 maythen be inserted through each opening 170 to engage a respective slot176 of the mounting bracket 174. The back portion 146 of housing 142 maythereby be removably mounted to the support structure by securing it tothe bracket 174.

The input port 59 of inlet manifold 42 may include a threaded connector178 configured to receive a threaded end of a diluent supply line. Theoutput port 72 of flush manifold 44 may include a nozzle 180 configuredto receive the dispense line 17 that conveys the output of thedispensing system 10 to the point of use. The nozzle 180 may include oneor more circumferential barbs 182 configured to resist movement of thesupply line and provide a secure fluid-tight connection between thenozzle 180 and the supply line.

FIG. 14 is an exploded view depicting an exemplary embodiment of thecontroller 12. The controller 12 may include a housing 186 having afront portion 188 and a back portion 190, and a Printed Circuit Board(PCB) 192. The PCB 192 may include the HMI 26, processor 28, I/Ointerface 30, and memory 32 of controller 12. The front portion 188 ofhousing 186 may include an opening 194 that provides access to the HMI26, and an opening 196 having a removable cover 198 that provides accessto a serial data port 200, such as a USB port. A connector 202 may beaffixed to a back facing side 204 of PCB 192 by one or more fasteners206. The back portion 190 of housing 186 may include an opening 208configured to receive the connector 202. The opening 208 may enable theI/O interface 30 of PCB 192 to be electrically coupled to the dispenser140, for example, by plugging a connectorized multi-conductor cable intothe connector 202.

It has been determined that during operation of a dispensing system thatuses eductors, there are operational scenarios in which two differentchemicals can mix within an eductor. The chemicals dispensed by aneductor are typically diluted at a diluent to chemical product ratio ofbetween 2.5:1 and 4.0:1. In some cases, different chemicals may reactwith each other, thereby creating a thick congealed plug. This plug maythen block the eductor so that little or no chemical is injected intothe flow of diluent. Embodiments of the invention may solve this problemby adding a check valve between the flush manifold and the dischargeport of the eductor.

FIG. 15 depicts a portion of a dispensing system in accordance with anembodiment of the invention that includes a plurality of eductors210-214 each having an inlet port 220-224 coupled to an inlet manifold226 by a respective selector valve 230-234, a pickup port 240-244, and adischarge port 250-254. Each of the selector valves 230-234 may includea solenoid 256-260 configured to open or close the selector valve230-234 in response to signals from the controller. In the exemplaryembodiment depicted, the discharge port 250 of eductor 210 is coupleddirectly to an intake port 262 of a flush manifold 270, and thedischarge ports 251-254 of the remaining eductors 211-214 are coupled tothe intake ports 263-266 of flush manifold 270 by check valves 272-275.The flush manifold 270 may comprise one or more modules 280-282 that areconfigured to be fluidically coupled to each other to form a flushmanifold having a desired number of intake ports.

The leftmost or “upstream” eductor 210 may be configured as a flusheductor that is used to provide diluent from the inlet manifold 226 tothe flush manifold 270 without injecting any chemical products. Thecontroller may activate the selector valve 230 coupling the flusheductor 210 to the inlet manifold 226 to flush chemical solutions fromthe flush manifold 270. The flush eductor 210 may be a “high flow”eductor as compared to the other eductors 211-214 to shorten flushtimes, or may comprise a suitably sized conduit that lacks a venturi.

In operation, the controller may sequentially activate one or more ofthe selector valves 231-234 for various periods of time to inject adesired amount of one or more chemical products into the flush manifold270. Once the mixture of chemicals defined by the dispensing applicationhas been dispensed, the controller may open the selector valve 230 offlush eductor 210 to flush the flush manifold 270 with diluent for aperiod of time sufficient to flush each dispensed solution to the pointof use.

By way of example, in a conventional dispensing system, two chemicalsmay come into contact as follows. The controller opens the selectorvalve of an eductor to dispense chemical A, which fills the flushmanifold and the dispense line with a solution containing chemical A.After the correct amount of chemical A has been delivered to the flushmanifold, the controller closes the selector valve. This may cause thepressure in the flush manifold to spike downward—and potentially gonegative—as the momentum of the previously dispensed solution causes thesolution to continue to flow through the dispense line, thereby pullinga vacuum on the flush manifold.

At this point, the controller may open the selector valve for the flusheductor, which pressurizes the flush manifold with diluent. Empiricaldata indicates that the pressure in the flush manifold may spike toapproximately 0.33 bar in response to the controller flushing the flushmanifold. This pressure may compress any air in the inactive eductors,thereby allowing any chemical solution remaining in the flush manifoldto enter the eductors. This effect was determined experimentally usingclear eductors in which a solution in the flush manifold was seen torise to a level at which it occupied approximately 25% of the volume ofthe eductor. Unexpectedly, it has been further determined that thesolution in the flush manifold rises to level in each eductor inproportion to the distance of the eductor from the last eductor used todispense a chemical solution. Thus, the level rises the most in theeductor adjacent to the most recently activated eductor.

The phenomenon wherein the level rises in accordance to the distancefrom the most recently used eductor may be due to the last eductor usedbeing relatively full of incompressible solution rather thancompressible air as may be found in eductors that have had time todrain. The same phenomenon may occur when one chemical is dispensedimmediately following another. In either case, the size of the pressurespike may also depend on the flow rate of the subsequent dispensingoperation. Thus, activation of high flow eductors and/or flush eductorsmay generate higher pressure spikes in the flush manifold than low floweductors. If the level of the dispense line rises above the level of theflush manifold at any point between the flush manifold and the point ofuse, this can also increase the pressure in the flush manifold ascompared to dispense lines that remain below the flush manifold. In anycase, when a selector valve opens, any solution present in the manifoldmay cause the pressure to increase as compared to when the flushmanifold is empty and/or open to the atmosphere.

The check valves 272-275 may be configured to prevent solutions beingdispensed by one or more of eductors 210-214 from back-flowing into theremaining inactive eductors as described above. This may prevent any ofthe chemicals dispensed by one eductor from entering one or more of theother eductors from the flush manifold 270. Advantageously, the checkvalves 272-275 may prevent different chemicals from coming into contactwithin the eductors 211-214 and plugging the venturi orifices thereof.

The check valves 272-275 may also provide a dynamic flood ring thatkeeps their respective eductor 211-214 in a constantly primed or“flooded” state by preventing solution from draining out of the eductorbetween activations. In addition, the check valves 272-275 may preventair from entering the eductor and drying out any remaining chemicalsolutions, which could create residue inside the eductors 211-214. Byindependently varying the resistance provided to the flow of fluidsthrough the eductor, the check valves 272-275 may provide more efficientoperation than would be provided by fixed flood ring.

Still further, the check valves 272-275 may provide an additionalbenefit of creating a dynamic barrier that opens when the eductor211-214 is activated and closes when the eductor 211-214 is idle toprevent contamination. Check valves 272-275 may be implemented ascartridges that can be added to existing systems as a separate part, orthe check valves 272-275 may be integrated into the eductors 211-214and/or flush manifold 270.

FIG. 16 is a cross-sectional view depicting additional details of theflush eductor 210, dispensing eductor 211, and module 280. Each eductor210, 211 includes a venturi 286, a converging passage 288 thatfluidically couples the venturi 286 to the inlet port 220, 221, adiverging passage 290 that includes a diffuser 291 and fluidicallycouples the venturi 286 to the discharge port 250-251, and a passage 292that fluidically couples the venturi 286 to the pickup port 240, 241.The module 280 may include a tapered outlet 294 that includes one ormore circumferential grooves 296, 298, a tapered inlet 300 including oneor more flexible rings 302, 304, and one or more openings 306, 308configured to receive the eductor 210, 211 and/or check valve 272. Thetapered inlet 300 may be configured to receive and form a fluid-tightseal with the tapered outlet of another module. The flexible rings 302,304 may be configured to engage the circumferential grooves of thereceived tapered outlet so that the received tapered outlet is heldposition with respect to the module receiving the outlet.

FIG. 17 is a cross-sectional view depicting additional details of anexemplary embodiment of the check valve 272. The check valve 272 mayinclude a barrel 310 having an upstream portion 312 configured toreceive the discharge port 251 of eductor 211 and a downstream portion314 configured to engage the opening 308 of module 280. The upstreamportion 312 of barrel 310 may define an upstream chamber 316 and thedownstream portion 314 of barrel 310 may define a downstream chamber318. The inner surface of barrel 310 may include a shoulder 320 betweenthe upstream and downstream chambers 316, 318 that provides support fora valve seat 322. The valve seat 322 may be held in place against theshoulder 320 by a valve seat retainer 324 and may define an opening 326between the upstream and downstream chambers 316, 318. In an alternativeembodiment of the invention, the shoulder 320 may be configured todefine the opening 326, in which case the valve seat 322 and valve seatretainer 324 may be omitted.

A closing member 328 (e.g., a ball) may be urged into engagement withthe opening 326 by an elastic member 330 (e.g., a spring). The elasticmember 330 may be configured to maintain the closing member 328 incontact with the opening 326 when fluids are not being dispensed throughthe check valve 272, and to allow the closing member 328 to move awayfrom the opening 326 when fluids are being dispensed through the checkvalve 272.

The eductor 211 may operate most efficiently when it is flooded, e.g.,when the diffuser 291 is filled with solution. A flooded diffuser 291may slow the velocity of the incoming diluent 60 as compared to a dry orempty diffuser, thereby ensuring a sufficient pressure drop across theeductor 211 to draw chemical product 18, 20 into the pickup port 241. Bycausing the closing member 338 to seal off the opening 326 when there isinsufficient flow through the eductor 211, the elastic member 330 mayenable the check valve 272 to operate as a dynamic flood ring thatprovides varying resistance to flow. The elastic member 330 may be heldin place by a support 332 that includes a support surface 334. Thesupport 332 may locate the elastic member 330 within the downstreamchamber 318 of barrel 310. The support surface 334 of support 332 may beconfigured to hold the closing member 328 in a fixed open position whenthe flow of fluid through the eductor 211 exceeds a threshold value. Thesupport surface 334 may thereby prevent damage to the elastic member 330during dispensing operations. In the event air is present in the inletmanifold, the elastic member 330 may allow the air to flowing throughthe eductor 211 to open the check valve 272 slightly. The subsequentflow of liquid may then fully open the check valve 272 to providemaximum flow.

Adding check valves 272-275 between the dispensing eductors 211-214 andthe flush manifold 270 may provide several advantages over conventionalsystems. For example, the check valves 272-275 provide a fluidic barrierbetween the dispensing eductors 211-214 and the flush manifold 270. Thisbarrier may prevent mixing of dissimilar chemicals in the venturi 286,converging passage 288, diffuser 291, diverging passage 290, or anyother portions of the eductors 211-214, thereby reducing the potentialfor clogging as described above. In addition, by preventing the diffuser291 from drying out between chemical dispense stages and/or dispensingoperations, the check valves 272-275 may prevent mineral salts and/ordissolved chemicals in the diluent from adhering to the inner surfacesof the eductors 211-214. Because further chemical products may adhere tothese deposits, eventually building up and clogging the eductor 211-214,the check valves 272-275 may also reduce the potential for clogs due tothe eductor 211-214 drying out between dispensing operations.

The dynamic flood ring feature of check valves 272-275 may improve theaccuracy of dispensing processes by maintaining the eductor 211-214 in awet state. When an eductor 211-214 is activated in a conventionaldispensing system, there may be an initial period during which theeductor 211-214 does not generate suction at the pickup port 241-244.This failure to generate suction is believed to be due to a lack ofliquid in the diffuser 291 at the beginning of the dispense stage. Thus,until enough diluent 60 has passed through the converging passage 288 toflood the diffuser 291, the eductor may fail to inject chemicals intothe diluent 60. Depending on the design of the eductor 211-214, thisflooding process can take 100 to 500 milliseconds. By isolating thediverging passage 290 from the flush manifold 280 when the eductor211-214 is inactive, the check valve 272-275 may keep the diffuser 291primed by preventing the chemical solution from draining out of thediverging passage after the selector valve 231-234 is deactivated. Thismay result in the diffuser 291 reaching a flooded state sooner afteractivation of the selector valve 231-234 than in dispensing systemslacking this feature. This in turn may result in the eductor 211-214drawing chemicals and injecting them into the diluent sooner and moreconsistently than in conventional eductor-based dispensing systems.

The check valves 272-275 may also reduce leaks caused by positivepressure at the outlet 294 of the flush manifold 270. For example, incases where the dispense line 17 is routed above the dispenser 14, thereis a potential for the dispense line 17 to remain full of diluent 60after flushing. Absent the check valves 272-275, if one of the checkvalves 58 coupling the feed line to the pickup port of an eductor isremove during a service call, the contents of the dispense line 17 maydrain back into the eductor and spill onto the floor. This issue may beeliminated with the use of check valves 272-275. Additional advantagesof the check valves 272-275 may include separation of pressure zonesduring flushing operations.

In general, the routines executed to implement the embodiments of theinvention, whether implemented as part of an operating system or aspecific application, component, program, object, module or sequence ofinstructions, or a subset thereof, may be referred to herein as“computer program code,” or simply “program code.” Program codetypically comprises computer-readable instructions that are resident atvarious times in various memory and storage devices in a computer andthat, when read and executed by one or more processors in a computer,cause that computer to perform the operations necessary to executeoperations and/or elements embodying the various aspects of theembodiments of the invention. Computer-readable program instructions forcarrying out operations of the embodiments of the invention may be, forexample, assembly language or either source code or object code writtenin any combination of one or more programming languages.

Various program code described herein may be identified based upon theapplication within which it is implemented in specific embodiments ofthe invention. However, it should be appreciated that any programnomenclature which follows is used merely for convenience, and thus theinvention should not be limited to use solely in any specificapplication identified and/or implied by such nomenclature. Furthermore,given the generally endless number of manners in which computer programsmay be organized into routines, procedures, methods, modules, objects,and the like, as well as the various manners in which programfunctionality may be allocated among various software layers that areresident within a typical computer (e.g., operating systems, libraries,API's, applications, applets, etc.), it should be appreciated that theembodiments of the invention are not limited to the specificorganization and allocation of program functionality described herein.

The program code embodied in any of the applications/modules describedherein is capable of being individually or collectively distributed as aprogram product in a variety of different forms. In particular, theprogram code may be distributed using a computer-readable storage mediumhaving computer-readable program instructions thereon for causing aprocessor to carry out aspects of the embodiments of the invention.

Computer-readable storage media, which is inherently non-transitory, mayinclude volatile and non-volatile, and removable and non-removabletangible media implemented in any method or technology for storage ofdata, such as computer-readable instructions, data structures, programmodules, or other data. Computer-readable storage media may furtherinclude RAM, ROM, erasable programmable read-only memory (EPROM),electrically erasable programmable read-only memory (EEPROM), flashmemory or other solid state memory technology, portable compact discread-only memory (CD-ROM), or other optical storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other medium that can be used to store the desired data and whichcan be read by a computer. A computer-readable storage medium should notbe construed as transitory signals per se (e.g., radio waves or otherpropagating electromagnetic waves, electromagnetic waves propagatingthrough a transmission media such as a waveguide, or electrical signalstransmitted through a wire). Computer-readable program instructions maybe downloaded to a computer, another type of programmable dataprocessing apparatus, or another device from a computer-readable storagemedium or to an external computer or external storage device via anetwork.

Computer-readable program instructions stored in a computer-readablemedium may be used to direct a computer, other types of programmabledata processing apparatuses, or other devices to function in aparticular manner, such that the instructions stored in thecomputer-readable medium produce an article of manufacture includinginstructions that implement the functions, acts, and/or operationsspecified in the flow-charts, sequence diagrams, and/or block diagrams.The computer program instructions may be provided to one or moreprocessors of a general-purpose computer, a special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the one or more processors,cause a series of computations to be performed to implement thefunctions, acts, and/or operations specified in the flow-charts,sequence diagrams, and/or block diagrams.

In certain alternative embodiments, the functions, acts, and/oroperations specified in the flow-charts, sequence diagrams, and/or blockdiagrams may be re-ordered, processed serially, and/or processedconcurrently consistent with embodiments of the invention. Moreover, anyof the flow-charts, sequence diagrams, and/or block diagrams may includemore or fewer blocks than those illustrated consistent with embodimentsof the invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the embodimentsof the invention. As used herein, the singular forms “a”, “an” and “the”are intended to include the plural forms as well, unless the contextclearly indicates otherwise. It will be further understood that theterms “comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, actions, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, actions,steps, operations, elements, components, and/or groups thereof.Furthermore, to the extent that the terms “includes”, “having”, “has”,“with”, “comprised of”, or variants thereof are used in either thedetailed description or the claims, such terms are intended to beinclusive in a manner similar to the term “comprising”.

While all the invention has been illustrated by a description of variousembodiments, and while these embodiments have been described inconsiderable detail, it is not the intention of the Applicant torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. The invention in its broader aspects istherefore not limited to the specific details, representative apparatusand method, and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of the Applicant's general inventive concept.

What is claimed is:
 1. A dispensing system comprising: a controllerconfigured to perform a dispensing operation including a dispense stagehaving a duration; an eductor having an inlet port that is selectivelyfluidically coupled to a source of a diluent by the controller duringthe dispense stage, and a discharge port configured to discharge achemical solution during the dispense stage; and a pressure sensorconfigured to provide a first signal indicative of a pressure of thediluent to the controller, wherein the controller determines theduration of the dispense stage based at least in part on the pressure ofthe diluent.
 2. The dispensing system of claim 1 further comprising: aconcentration sensor configured to provide a second signal to thecontroller indicative of a characteristic of the diluent or the chemicalsolution, wherein the controller determines the duration of the dispensestage based at least in part on the characteristic.
 3. The dispensingsystem of claim 2 wherein the characteristic is a concentration of asubstance in the diluent or the chemical solution.
 4. The dispensingsystem of claim 3 wherein the substance is a mineral, and the durationof the dispense stage is proportional to the concentration of thesubstance.
 5. The dispensing system of claim 3 wherein the substance isa chemical product, and the duration of the dispense stage is inverselyproportional to the concentration of the substance.
 6. The dispensingsystem of claim 2 wherein the controller is further configured to:capture a sequence of readings indicative of the characteristic; comparethe sequence of readings to a predetermined pattern associated with thedispensing operation; and if the sequence of readings is not inaccordance with the predetermined pattern, determine there is a problemwith the dispensing operation.
 7. The dispensing system of claim 1wherein the dispensing operation includes a flush stage, and thecontroller is further configured to: determine the duration of the flushstage based at least in part on the pressure of the diluent.
 8. Thedispensing system of claim 7 wherein the dispensing operation is definedby a dose of a chemical product and a total volume of solution to bedispensed, and the controller is further configured to: determine a flowrate of the diluent through the eductor based at least in part on thepressure of the diluent; determine a concentration of the chemicalproduct in the chemical solution discharged by the eductor based atleast in part on the pressure of the diluent; and determine the durationof the dispense stage based at least in part on the dose of the chemicalproduct, the concentration of the chemical product in the chemicalsolution discharged by the eductor, and the flow rate of the diluentthrough the eductor.
 9. The dispensing system of claim 8 wherein thecontroller is further configured to: determine a volume of the chemicalsolution discharged by the eductor during the dispense stage based atleast in part on the duration of the dispense stage and the flow rate ofthe diluent; and determine the duration of the flush stage based atleast in part on a difference between the volume of the chemicalsolution discharged during the dispense stage and the total volume ofsolution to be dispensed.
 10. A method of performing a dispensingoperation, the method comprising: receiving, at a controller configuredto perform the dispensing operation, a first signal indicative of apressure of a diluent; determining, by the controller, a duration of adispense stage of the dispensing operation based at least in part on thepressure of the diluent; and causing, by the controller, the diluent toflow through an eductor for the determined duration of the dispensestage.
 11. The method of claim 10 further comprising: receiving, at thecontroller, a second signal indicative of a characteristic of thediluent or a chemical solution discharged from a discharge port of theeductor; and determining the duration of the dispense stage based atleast in part on the characteristic.
 12. The method of claim 11 whereinthe characteristic is a concentration of a substance in the diluent orthe chemical solution.
 13. The method of claim 12 wherein the substanceis a mineral, and the duration of the dispense stage is proportional tothe concentration of the substance.
 14. The method of claim 12 whereinthe substance is a chemical product, and the duration of the dispensestage is inversely proportional to the concentration of the substance.15. The method of claim 11 further comprising: capturing a sequence ofreadings indicative of the characteristic during the dispensingoperation; comparing the sequence of readings to a predetermined patternassociated with the dispensing operation; and if the sequence ofreadings is not in accordance with the predetermined pattern,determining there is a problem with the dispensing operation.
 16. Themethod of claim 10 wherein the dispensing operation includes a flushstage, and further comprising: determining the duration of the flushstage based at least in part on the pressure of the diluent.
 17. Themethod of claim 16 wherein the dispensing operation is defined by a doseof a chemical product and a total volume of solution to be dispensed,and further comprising: determining a flow rate of the diluent throughthe eductor based at least in part on the pressure of the diluent;determining a concentration of the chemical product in a solutiondischarged by the eductor based at least in part on the pressure of thediluent; and determining the duration of the dispense stage based atleast in part on the dose of the chemical product, the concentration ofthe chemical product in the solution discharged by the eductor, and theflow rate of the diluent through the eductor.
 18. The method of claim 17further comprising: determining a volume of the solution discharged bythe eductor during the dispense stage based at least in part on theduration of the dispense stage and the flow rate of the diluent; anddetermining the duration of the flush stage based at least in part on adifference between the volume of the solution discharged during thedispense stage and the total volume of solution to be dispensed.
 19. Acomputer program product for performing a dispensing operation, thecomputer program product comprising: a non-transitory computer-readablestorage medium; and program code stored on the non-transitorycomputer-readable storage medium that, when executed by one or moreprocessors, causes the one or more processors to: receive a signalindicative of a pressure of a diluent; determine a duration of adispense stage of the dispensing operation based at least in part on thepressure of the diluent; and cause the diluent to flow through aneductor for the determined duration of the dispense stage.
 20. Adispensing system comprising: a flush manifold including a plurality ofintake ports; an eductor having an inlet port that is selectivelyfluidically coupled to a source of a diluent, a pickup port fluidicallycoupled to a source of a chemical product, and a discharge portconfigured to discharge a chemical solution in response to the diluentbeing coupled to the inlet port; and a check valve coupling thedischarge port of the eductor to one of the intake ports of the flushmanifold.
 21. The dispensing system of claim 20 wherein the check valvecomprises: an upstream chamber; a downstream chamber fluidically coupledto the upstream chamber by an opening; and a closing member configuredto fluidically isolate the downstream chamber from the upstream chamberby covering the opening absent a flow of fluid from the upstream chamberto the downstream chamber.
 22. The dispensing system of claim 21 whereinthe check valve further comprises: an elastic member that urges theclosing member into contact with the opening absent the flow of fluidfrom the upstream chamber to the downstream chamber.
 23. The dispensingsystem of claim 21 wherein the opening is defined by a valve seat. 24.The dispensing system of claim 20 wherein the check valve provides adynamic flood ring that has a first resistance to the flow of fluidthrough the eductor in a first state, and a second resistance to theflow of fluid higher than the first resistance in a second state. 25.The dispensing system of claim 24 wherein the first state is an openstate and the second state is a closed state.
 26. The dispensing systemof claim 24 wherein the check valve maintains the eductor in a floodedstate when the dynamic flood ring is in the second state.
 27. A methodof performing a dispensing operation, comprising: providing a flow ofliquid to an inlet port of an eductor sufficient to flood the eductor;in response to the flow of liquid being provided to the inlet port,providing a first resistance to the flow of liquid out of a dischargeport of the eductor; and in response to the flow of liquid to the inletport being reduced, providing a second resistance to the flow of liquidout of the discharge port.
 28. The method of claim 27, wherein the firstresistance is lower than the second resistance.
 29. The method of claim27 wherein the first resistance optimizes suction at a pickup port ofthe eductor, and the second resistance maintains the eductor in aflooded state.
 30. The method of claim 27 wherein: providing the firstresistance comprises moving a closing member out of contact with anopening in response to the flow of liquid, the movement compressing anelastic member, and providing the second resistance comprises moving theclosing member into contact with the opening in response to urging bythe elastic member.